Wait for event

Hi,

Below is my requirement. Any ideas how to make the program wait?

I have Z program has 4 different process chains that needs to be triggered. When the user executes the program, I trigger an event using FM. A process chain in BW will get executed once this event is triggered.

Now I want my main program to wait until the first process chain is completed to trigger the next event which will start another process chain. how do I achieve this?

I do not want to have a wait until N seconds (in a loop) and then query some table to check if the first process chain is completed. Is there any other way to achieve this?

Thanks,

Vikram.M